couple : 多指在一起或彼此有关系的两个人或两个同样的事物。
- The doctor said my leg should be better in a couple of days.
- A couple of people objected to the proposal, but the vast majority approved of it.
- We'll have to wait another couple of hours for the paint to dry.
- She'll be retiring in a couple more years.
- The weather's been terrible for the last couple of days.
- Many economists expect unemployment to fall over the next couple of months.
- I'm sorry I didn't call you, but I've been very busy over the past couple of weeks.
pair : 含义广泛，可指人或物。用于物时，指两个互属的事物，缺此或失彼都会失去使用价值，或指由相对称的两部分构成的一件东西。
- a pair of shoes/gloves
- a pair of scissors/glasses
- I can't find a matching pair of socks.
- He packed two pairs of trousers and four shirts.
- I'd like you to do this exercise in pairs (= in groups of two).
- They seem a very happy pair.
- What have the pair of you been up to?